[ibis-macro] Analog Model Isolation Definition
- From: "Bob Ross" <bob@xxxxxxxxxxxxx>
- To: "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
- Date: Tue, 20 Mar 2012 14:56:39 -0700
All:
Per the discussion today on the block interface definition,
here is a derivation based on BIRD122 for just s2p 2-ports (but should
apply to s4p files with more math). It shows the gain sensitivity to
the explicit S11 term for TX and S22 term for RX from a reference impedance
definition (e.g., TX: S11=0 or 50 ohm to infinite impedance S11 = 1
and RX: S22=0 to zero impedance S11=-1).
In both cases, the transfer function S21 term is changed by a
factor of 2 (assuming no S12 term). This is equivalent
to specifying the isolation interfaces with a unity gain ideal voltage
amplifier.
//www.freelists.org/post/ibis-macro/Eelement-in-analog-model-BIRD,1
Sorry, but some of the prior material may have involved some
lost or private e-mails and also a presentation or e-mail shown to
the ATM committee according to questions and exchanges in
the Dec. 14, 2010 minutes including:
Walter showed an email from Fangyi:
- Fangyi: The equation is at the bottom
- Bob: We have defined S12 as zero
- The real voltage gain is a function of S11
- Todd: Is this because S11 can affect V1 and therefore V2?
- Fangyi: No
- If V1 was fixed V2 would still be affected by S11
- Bob: The defaults should be zero for series impedances and
infinity for impedances to ground.
http://www.vhdl.org/ibis/macromodel_wip/minutes/20101214/mikelabontecisco/Mi
nutes%20for%20the%2012-14-2010%20ibis-atm%20meeting/20101214.txt
The main point is that the complete interface needs to be known and
defined in the Specification (for S-parameters and perhaps
different for a SPICE model) to get the proper gain (S21 term).
Bob
--
Bob Ross
Teraspeed Consulting Group, LCC
http://www.teraspeed.com
bob@xxxxxxxxxxxxxx
Direct : 503-246-8048
Teraspeed Labs: 503-430-1065
Headquarters: 401-284-1827
Teraspeed is a registered service mark of Teraspeed Consulting Group LLC
---------------------------------------------------------------------
IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/
IBIS Macro reflector: //www.freelists.org/list/ibis-macro
To unsubscribe send an email:
To: ibis-macro-request@xxxxxxxxxxxxx
Subject: unsubscribe
Other related posts:
